Process of treating fabrics



UNITED FFlC HERBERT PLATT, 0F CUMBERLAND, MARYLAND, ASSIGNOR TO CECLANESE CORPORA- TION OF AMERICA, A CORIORATION OF DELAWARE PROCESS OF TREATING FABRICS No Drawing.

This invention relates to the treatment of yarns or fabrics made of or containing organic esters of cellulose such as cellulose formats, cellulose acetate, cellulose propionate, etc. whereby the creasing of such materials is avoided.

An object of this invention is to treat fabrics containing organic esters of cellulose in such a manner that when they are subsequently subjected to dyeing operations, the creasing or wrinkling of the fabric will be avoided.

Another object of my invention is to partially saponify cellulose ester fabrics, thereafter dyeing the same in any desired manner. )ther objects of my invention will appear in the following detailed description.

In dyeing certain classes of fabrics, it has been difficult to obtain a finished product free from creases. This necessitated the employment of special machines and processes which were not only cumbersome but also were not uniformly successsful. Thus it has been considered inadvisable to dye certain types of cellulose ester fabrics on a winch due to the excessive creasing which resulted from such a dyeing operation.

I have now found that this objectionable creasing can be eliminated if the fabric to be dyed is first subjected to a surface saponification and then dyed on a winch in the usual manner. This unexpected result is most noticeable in such fabrics as are wet out with difhculty, because of. their construction or because of their composition. Thus fabrics containing high twist yarns such as crepes are eminently suited for treatment in accordance with the present process. The surface saponification of the cellulose ester present in the fabric no doubt facilitates the wetting out of the fabric and this in turn prevents the formation of creases.

The manner in which the surface saponification is effected is immaterial in so far as the present invention is concerned. I have found that the tendency of certain fabrics to The alkaline hath used for partially sapon ifying the cellulose acetate contained in the Application filed October 26, 1928. Serial No. 315,346.

fabric or yarn may be either of lowconcentration or of high concentration depending on the temperature of treatment. If an alkaline solution of low concentration is used,-

phenolate, sodium or potassium sulp sodium or potassium silicate, or tri-sodiuni phosphate. In order to promote intense surface saponification of the yarn containing the organic ester of cellulose, buffer salts or modifying agents such as soap, sodium acetate, horax or alcohol, etc. may be added to the saponifying bath.

W'hen alkaline solutions of low hydroxyl concentration are employed, the bath should contain at least 0.2 grams of sodium hydroxide or the equivalent amount of other alkaline substances per liter of solution, when temperatures of 80 C. are employed: Vllhile I do not limit myself to the specific con centrations, l have found that solutions having a hydroxyl ion content corresponding to 0.4, 0.5, 0.6 or 0.7 grams of sodium. hydroxide per liter, give eminently satisfactory results. The temperature of the bath is maintained at 60 to 90 C. and preferably at about 80 C. However, after saponification of the cellulose acetate textile material had been initiated, the saponifying bath may contain less sodium hydroxide, sincesaponification then proceeds in a bath containing hydoxyl ions in amounts corresponding to less than 0.2 grams of sodium hydroxide per liter. T he saponification may proceed to any desired extent, say 3% or 5 to 10% or more. These percentages represent the percent of weight the cellulose acetate has lost through the saponification treatment.

portions of soap to the solution may be varied within wide limits, I have found thatthe presence of 0.5 grams to 10 grams of soap per liter of solution produces satisfactory results.

In one mode of carrying out my invention with the use of solutions containing alkali in low concentrations, the goods are scoured in an open bath on strings or in any suitable machine such as a jig, with a bath containing olive oil soap for an hour or two. The goods ma then be removed from the bath and saponifie in a separate bath containing fresh water and alkali, but they are preferably saponified directly in the general scouring bath by the addition of a requisite amount of caustic soda. In one mode of partially saponifyin the fabric containing the organic ester of ce lulose with an alkaline solution of low concentration, the fabric is immersed in a bath of such large volume that it contains sufficient alkali to cause the desired de gree of saponification but which is not of such concentration to exceed the maximum permissible concentration of alkali material at the temperature to be employed. Thus for example, in saponifying a fabric consisting wholly of cellulose acetate of approximately 54% acetyl value, I have found that a bath of up to to 180 times the weight of the fabric can advantageously be used, and that such bath should preferably contain an amount of caustic soda to the extent of 4 to 8% of the weight of the fabric, when a bath temperature of 80 C. is used.

vor if the temperature of the bath is other than 80 6., the proportions: will be varied accordingly. Likewise it is apparent that when smaller amounts of alkaline material are used the volume of the saponification bath may be correspondingly decreased.

In another mode of carrying out my invention when alkaline solutions of low concentrations are employed, the fabric containing the yarns of cellulose acetate is treated in an alkaline bath of comparatively small volume and containing a relatively small amount of caustic soda. As the saponification proceeds, further quantities of caustic soda are added in small increments, until the desired degree of saponification hastaken place. Until the operator has gained suiiicient experience, it is preferable to check up the amount of caustic soda in the bath by titration with sulphuric acid to insure that the amount of caustic soda added is not suf-' ficient to cause the saponifying bath to have a concentration exceeding the maximum permissible degree.

When concentrated alkaline solutions are used, the concentration of the alkali solution preferably corresponds to from 5 to 20% of caustic soda by Weight. I have found that the use of 10% caustic soda solution is suitable for causing the cellulose acetate fabalso contain such assistants as soap, sodium acetate, etc. The alkali solutionmay be applied to the fabric containing the organic esters of cellulose in any suitable manner. However, I prefer to apply the. caustic soda when applied in comparatively concentrated solution to the fabric by padding the caustic solution onto the fabric and then permitting the same to stand for an appreciable length of time as will be described below. The temperature of treatment is preferably room temperature and should not exceed 35 C. for obtaining the best results.

The fabric or yarn containing the organic ester of cellulose when treated with a saponifying solution by any of the above described methods is intensely saponified on the surface of the yarn. By intense surface saponification is meant the concentration of saponifi' cation of the cellulose ester material on the surface of the yarn, while the interior of the yarn is very little affected and, therefore, consists essentially of cellulose esters. This is indicated by the fact that when cellulose acetate fabrics are treated in accordance with the above described methods, the solubility of the fabric in acetone is relatively high, and the fabric may be dyed with cotton dyes because of the fact that the surface of the yarn is essentially reconstituted cellulose or approximately so. 0

Thus the cellulose acetate fabric to be saponified can be plaited. A woven fabric consisting wholly of cellulose acetate yarn is plaited and strung, and is then immersed in a bath in which the ratio of water to fabric is between to 1 to to 1. This bath contains soap to the extent of one gram per liter of bath and the bath temperature is maintained at 80 C.

The fabric is treated in this soap bath for three-quarters of an hour.

The fabric is then raised out of the bath, caustic soda in an amount equal to 6% of the Weight of the fabric is added to the bath. and after the solution is homogeneous, the fabric is then immersed in the bath and is treated therein for approximately three hours while the bath temperature is maintained at 80 C. The fabric is then lifted, washed ofl in water at 60 0., and then may be dyed in the manner set forth below.

If it is desired to saponify the fabric with a concentrated alkali solution, the fabric can be padded through rolls that are covered with several thicknesses of'heavy cotton lapping or other absorbent material, using a bath containing 100 parts of water and 10 parts of caustic soda. The caustic soda solution is at room temperature, and the fabric is given two runs through the pad. The nip on the pad is arranged so that the fabric picks up an amount of solution equal to its own weight. After the second run on the pad, the roll of fabric is allowed to run 15 minutes, and the solution is then very lightly extracted on the roll. The fabric with the remaining solution is allowed to stand overnight at room temperature. In carr ing out this process, it is important to give ue heed to the strength of the caustic soda solution and to the tem erature of treatment, which should prefera ly not exceed 35 G. Likewise it is of importance that the fabric should be batched with a minimum amount of tension, and that the caustic soda solution should be allowed to remain on the fabric for a period comparable to that of overnight. After standing overni ht,the fabric is rinsed in water and is rea y for. dyeing.

This second process of saponification can be modified as desired by making up a bath of 100 parts of water and 5 parts of caustic soda, with some thickening agent added if desirable. The fabric is then padded through rolls, giving it one run through the pad. The nip is so arranged that the fabric picks up an amount of solution equal to its own weight. The fabric is then immediately passed over and around rotating drums or cans that are heated to about C. until the fabric is dry. The fabric may then be immediately dyed.

The foregoing examples are but a few methods of treating a fabric'to saponify the same preparatory to dyeing the fabric. I have found that all of these methods impart to the fabric a property of being easily wetted out, which ena les the same to be dyed on a winch without becoming creased or if the fabric is creased while in the greige, the creases are eliminated. This is a decided advantage for it has been necessary heretofore to dye most of the heavy fabrics on an Etoile or Star machine. This not only prolonged the time of dyeing but also necessitated the use of false selved es on the fabric to avoid string marks. After the fabric has been saponified, in any desired manner, it is vacuum extracted and dried in a stove. The fabric may then be dyed on the winch in any suitable dye bath without any creasing of the fabric resulting. If desirable the fabric before being saponified may be scoured in a boil oif tank and subjected to a delustering operation.

As'an illustration of my invention the following example is given. The quantities set out are based upon the treatment of 85 lbs. of crepe marocain fabric, made from yarns of cellulose acetate.

The fabric is folded and strung along on a plaiting machine in one-yard plaits and on this particular type of fabric, 4.- to 5 plaits are strung together and 4 strings are used across the piece. The fabric is first scoured for onehalf hour at 80 C. in a boil-off tank containing 6800 liters of water to which 120 liters of a 10% olive oil soap solution and 30 liters of a dispersion of xylene in Turkey-red oil have been added. If it is desired to deluster the fabric the temperature of the bath is raised to 87 C. and maintained at that term pera-ture for about one-half hour.

The temperature of the bath is now dropped to 80 C., the fabric raise-d out of the bath on a lifting frame and2300 grams of caustic soda added and the whole is stirred. After the soda is dissolved the fabric is reintroduced and the goods worked at 80 C. for about 3 hours, when the fabric is tested to determine the degree of saponification. The fabric is then vacuum extracted, dried in a stove and then dyed at 80 C. on a winch in any suitable dyeing bath conta1ning gram per liter of olive oil soap and 4 cc. per liter of a dispersion of xylene in Turkey-red oil. The goods are then run over a vacuum extractor-dried in a, stove or ma.-

chine, steamed a little on the tenter and then :1

subjected to light calendaring or button breaking if necessary. The fabric is found to be evenly dyed and entirely free of creases, even though the fabric in the greige may have shown creasing.

While the above example described the process as applied to crepemarocain, a flat crepe, the invention is not limited to this particular type of fabric. Any crepe fabric and most any other heavy fabric containing organic esters of cellulose and which'is subject to creasing can be treated in accordance with this invention to overcome this objectionable feature. Thus, for example, tricot fabric, and milanese fabric may also be treated in accordance with this process. The process can be applied to any such types of fabric whether the same is made entirely of cellulose acetate or other 'organic esters of cellulose or mixtures of such cellulose esters any creases which the fabric in the greige possessed. The process will also serve to increase the resistance of the fabric to hot pressing. Where the normal luster of the fabric is desired, the delustering step outlined in the example may be omitted.

Having described my invention what I claim and desire to secure by Letters Patent 1. Process of treating fabrics containing organic esters of cellulose which comprises subjectin the fabric to partial saponification, drylng the same and then thoroughly wetting out the fabric and dyeing the fabric on a winch.

2. Process of treating-fabrics containing cellulose acetate which comprises subjecting the fabric to partial saponification, drying the same and then thoroughly wetting out the fabric and dyeing the fabric on a winch.

3. Process of treating crepe fabrics containing organic esters of cellulose which comprises subjecting the fabric to partial saponification, drying the same and then thoroughly wetting out the fabric and dyeing the fabric on a winch. r

4. Process of treating delustered fabrics containing cellulose acetate which comprises partially saponifying the'delustered fabric, drying the saponified fabric and then thoroughly wetting out the same and dyeing the thus treated fabric on a winch.

5. Process of treating delustered crepe fabrics containing cellulose acetate which comprises partially saponifying the delustered fabric, drying the saponified fabric and then thoroughly wetting-out the same'and dyeing the'thus treated fabric on a winch.

6. Process of treating delustered fabrics containing organic esters of cellulose which comprises partially saponifying the delusteredfabric, vacuum-extracting and drying the thus treated fabric, wetting out the fabric and subjecting the'same to a dyeing operation on a winch.

7. A process for eliminating creases from fabrics in the greige containing organic esters of cellulose which comprises saponifying the surface of the yarns of they celluloseester,

drying the partially saponified fabric and then dyeing the fabric on a winch.

8. In theprocess of dyeing fabrics containing organic esters, of cellulose, the'steps of partially saponifying the fabric and then drying it prior to dyeing the same on a winch.

9. In the processof d eing fabrics containing cellulose acetate, the steps of partially saponifying the fabric and then drying it prior to dyeing the same on a winch.

10. In the process of dyeing fabrics containing organic esters of cellulose, the step of saponifying the surface of the yarns comprising said fabric and then drying said fabric prior to dyeing the same on a WlIlCll.

11. In the process of dyeing fabrics containing cellulose acetate, the step of saponifying the surface of the yarns comprising said fabric and then drying said fabric prior to dyeing the same on a winch.

In testimony whereof, I have hereunto subscribed my name.

HERBERT PLATT. 

